What Happens After Someone Clicks a Phishing Email? A Microsoft 365 Incident Walkthrough

Every organization receives phishing emails. While Microsoft 365 includes multiple layers of protection to block malicious messages, no email security solution can stop every attack. That's why it's important to understand what happens if an employee clicks a phishing link—and how Microsoft 365 security features help detect and respond to suspicious activity.

Many people assume that simply clicking a phishing link immediately infects a computer. In reality, the outcome depends on what happens next. Some phishing campaigns only attempt to steal usernames and passwords, while others deliver malware or try to gain long-term access to business data.

Let's walk through a realistic phishing scenario and see how Microsoft's security tools can help at every stage.

Step 1: A Convincing Phishing Email Arrives

Imagine an employee receives what appears to be a Microsoft 365 notification asking them to review a shared document. The email includes Microsoft branding, a familiar layout, and a button labeled Open Document.

Other common phishing lures include:

• Fake invoice or payment requests

• Password expiration notifications

• Multi-factor authentication (MFA) alerts

• HR or payroll messages

• Cloud storage sharing notifications

Although Microsoft Defender for Office 365 helps identify and block many phishing emails before they reach users, attackers continually change their tactics to evade detection.

At this stage, the employee has only received the email. No compromise has occurred.

Step 2: The User Clicks the Link

Clicking a phishing link alone does not necessarily compromise the device.

Several outcomes are possible:

• The employee recognizes something is wrong and closes the page.

• The fake website attempts to collect Microsoft 365 credentials.

• The site prompts the user to approve an MFA request or enter a verification code.

• The page attempts to download malicious software.

• The browser blocks suspicious content before anything is downloaded.

The greatest risk usually occurs when the user enters their Microsoft 365 credentials into a fraudulent sign-in page. Those credentials may then be used by attackers to attempt access to the organization's Microsoft 365 environment.

Step 3: The Attacker Attempts to Sign In

If credentials are successfully stolen, attackers typically try to authenticate to Microsoft 365 immediately.

Depending on your organization's security configuration, Microsoft Entra ID may detect suspicious behavior such as:

• Sign-ins from unfamiliar countries or regions

• Sign-ins from anonymous IP addresses

• Unusual sign-in properties

• Suspicious authentication patterns

• Multiple failed authentication attempts

Organizations licensed for Microsoft Entra ID Protection may also receive automated risk detections that identify potentially compromised accounts.

At this point, Microsoft begins collecting valuable security telemetry that administrators can use during an investigation.

How Microsoft 365 Helps Detect a Phishing Email Incident

Microsoft provides several security services that work together to identify suspicious activity throughout a phishing email incident.

Microsoft Defender for Office 365

• Detects phishing emails

• Scans malicious attachments

• Rewrites and checks suspicious links using Safe Links (where licensed)

• Identifies phishing campaigns targeting multiple users

Microsoft Entra ID

• Records every authentication attempt

• Provides detailed sign-in logs

• Identifies risky sign-ins and risky users (with applicable licensing)

Microsoft Defender XDR

Microsoft Defender XDR correlates alerts from Microsoft Defender for Office 365, Microsoft Defender for Endpoint, Microsoft Defender for Identity, Microsoft Entra ID, and other Microsoft security products to help security teams investigate incidents from a single portal.

Microsoft Defender for Endpoint

If malware is downloaded or malicious activity occurs on a managed device, Microsoft Defender for Endpoint can generate alerts, provide device timelines, and support containment actions such as device isolation.

Step 4: Investigating the Incident

Once suspicious activity is detected, administrators should begin investigating immediately.

Useful places to review include:

• Microsoft Entra ID sign-in logs

• Risk dete-ctions (where available)

• Microsoft Defender alerts

• Unified Audit Log

• Mailbox activity

• Inbox rules

• Email forwarding rules

• Recently accessed devices

• Recent administrative actions

One particularly important step is checking whether attackers created mailbox forwarding or inbox rules to secretly redirect future emails. These techniques are commonly used to maintain access to sensitive communications without immediately alerting users.

Step 5: Containing the Attack

Microsoft recommends taking prompt action to prevent additional damage.

Typical containment steps include:

• Block the user's sign-in temporarily.

• Reset the user's password.

• Revoke existing refresh tokens to require new authentication.

• Require the user to complete MFA again if appropriate.

• Remove unauthorized inbox or forwarding rules.

• Investigate other users who may have received the same phishing email.

• Isolate affected devices if malware is suspected.

Quick containment helps minimize the risk of data theft and prevents attackers from establishing persistent access.

Step 6: Recovery

After the immediate threat has been contained, administrators should verify that the attacker no longer has access.

Recovery activities may include:

• Reviewing recent sign-in activity for additional suspicious access.

• Confirming that no unauthorized applications have been granted permissions.

• Restoring deleted emails or files if necessary.

• Reviewing Conditional Access policies.

• Monitoring the account for continued suspicious behavior.

• Documenting the incident and lessons learned.

Recovery is also an opportunity to identify security improvements that can reduce the likelihood of similar incidents in the future.

How to Reduce the Risk of Future Phishing Attacks

No organization can completely eliminate phishing attempts, but several Microsoft security features significantly reduce risk.

Consider implementing the following best practices:

• Enable multi-factor authentication (MFA). Where possible, use phishing-resistant authentication methods such as passkeys or FIDO2 security keys.

• Enable Safe Links and Safe Attachments in Microsoft Defender for Office 365 if your licensing includes these features.

• Implement Conditional Access policies to restrict risky sign-ins.

• Review Microsoft Secure Score recommendations regularly.

• Monitor sign-in logs and security alerts.

• Disable legacy authentication protocols if they are still enabled.

• Run Attack Simulation Training to educate users using realistic phishing campaigns.

• Provide ongoing security awareness training for employees.

Security works best when technology and user awareness complement one another.

Conclusion

A phishing email does not automatically result in a successful cyberattack, but every suspected phishing attempt should be treated seriously. The faster suspicious activity is detected, investigated, and contained, the lower the risk of unauthorized access, data loss, or business disruption.

Microsoft 365 includes powerful security capabilities that help organizations detect suspicious emails, investigate unusual sign-ins, monitor user activity, and respond to incidents efficiently. By understanding how these tools work together and following Microsoft's recommended incident response practices, small and medium-sized businesses can significantly strengthen their defenses against phishing attacks.

If you're unsure whether your Microsoft 365 environment is configured to detect and respond to phishing effectively, reviewing your security settings and response procedures is an excellent place to start.

We help small and medium-sized businesses secure their Microsoft 365 environments by implementing Microsoft's recommended security best practices, strengthening phishing protection, and responding to security incidents. If you'd like to assess your current security posture or improve your defenses against phishing attacks, we're here to help.

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